1. Field of the Invention
The present invention relates to a detector apparatus and a charged particle beam system.
2. Description of the Related Art
A sample stage for use in an electron microscope can move a sample into a specified position and tilt the sample through a specified angle (see, for example, patent document 1).
When a sample is observed with an electron microscope, the user moves the sample in order either to search for a subject to be observed or to place the sample in the center of the field of view. Furthermore, the user moves the sample in order to correct or adjust the height or tilt angle of the sample.
In electron microscopy, coordinates indicating the position of a sample are displayed on a display screen. The user moves the sample while using as a reference the displayed coordinates indicating the sample position.
Furthermore, in an electron microscope, a control system for a sample stage controls the sample stage, also based on the coordinates indicative of the position of a sample. In addition, where image analysis software for reconstructing a three-dimensional image of a sample tomographically is used, the tilt angle of the sample is used as a parameter in analyzing the image or structure.
In this way, in an electron microscope, information about the position and tilt angle of a sample is used in various situations. Accordingly, there is a demand for a detector apparatus capable of detecting the position and tilt angle of a sample stage with high resolution and also with high reliability.